【The Java™ Tutorials】【Regular Ex

Creating a Pattern with Flags

Pattern.compile方法能够接收一个flags参数，改变模式匹配的方式。比如忽略字母的大小写：

//不区分大小写
Pattern pattern = Pattern.compile(console.readLine("%nEnter your regex: "),
                                Pattern.CASE_INSENSITIVE);

还能够组合多个flag：

//组合多个flag
pattern = Pattern.compile("[az]$", Pattern.MULTILINE | Pattern.UNIX_LINES);

Embedded Flag Expressions

It's also possible to enable various flags using embedded flag expressions. Embedded flag expressions are an alternative to the two-argument version of compile, and are specified in the regular expression itself.

Embedded Flag Expressions

各个flag和对应的嵌入式表达式如下：

Constant	Equivalent Embedded Flag Expression
Pattern.CANON_EQ	None
Pattern.CASE_INSENSITIVE	(?i)
Pattern.COMMENTS	(?x)
Pattern.MULTILINE	(?m)
Pattern.DOTALL	(?s)
Pattern.LITERAL	None
Pattern.UNICODE_CASE	(?u)
Pattern.UNIX_LINES	(?d)

嵌入式组合多个flag的方式如下：

Embedded Flag Expressions